Abstract: A combined detector capable of simultaneously detecting both a value indicating a physical/chemical phenomenon such as a pH value and the intensity of an energy beam such as light. The combined detector comprises a physical/chemical phenomenon detecting system (10) and an energy beam detecting system. The physical/chemical phenomenon detecting system (10) has a sensing section (21) whose potential varies with a physical/chemical phenomenon, a charge supply section (22) for supplying first charge to the sensing section, a charge supply control section (23) provided between the sensing section (21) and the charge supply section (22), a first charge storage section (26) for storing the first charge transferred from the sensing section (21), and a charge transfer control section (27) provided between the sensing section (21) and the first charge storage section (26).

Abstract: A self-contained, fully automated, biological assay-performing apparatus includes a housing; a dispensing platform including a controllably-movable reagent dispensing system, disposed in the housing; a reagent supply component disposed in the housing; a pneumatic manifold removably disposed in the housing in a space shared by the dispensing platform, removably coupled to a fluidic transport layer and a plurality of reservoirs, wherein the fluidic transport layer, the reservoirs, and a test sample to be introduced therein are disposed in the housing in the space separate from the dispensing platform; a pneumatic supply system removably coupled to the pneumatic manifold in the housing in a space separate from the dispensing platform; and a control system coupled to at least one of the dispensing platform and the pneumatic supply system, disposed in the housing.

Abstract: Disclosed is a spotter device and methods for the formation of microassays, biochips, biosensors, and cell cultures. The spotter may be used to deposit highly concentrated spots of protein or other materials on a microarray slide, wafer, or other surface. It may also be used to perform various chemistry steps on the same spots. The spotter increases the surface density of substances at each spot by directing a flow the desired substance (or a solution thereof) over the spot area until surface saturation is accomplished. The spotter may be loaded by well plate handling equipment. The spotter uses wells, microfluidic conduits, and orifices to deposit proteins, other biomolecules, or chemicals on a spot on a separate surface. Each orifice is connected to two wells via microconduits. When the spotter contacts a surface, a seal is formed between the orifices and the surface. The same or different substances may be flowed across each orifice. Any number of orifices may be incorporated into a spotter.

Abstract: A test module for detecting target nucleic acid sequences in a fluid, the test module having an outer casing having a receptacle for receiving the fluid containing the target nucleic acid sequences, electrochemiluminescent (ECL) probes having an ECL luminophore for emitting photons when in an excited state and a functional moiety for quenching photon emission from the ECL luminophore by resonant energy transfer, electrodes for receiving an electrical pulse to excite the ECL luminophores, and, a detection photosensor for exposure to the photons emitted by the ECL luminophores.

Abstract: Fluid-based no-moving part logic devices are constructed from complex sequences of micro- and nanofluidic channels, on-demand bubble/droplet modulators and generators for programming the devices, and micro- and nanofluidic droplet/bubble memory elements for storage and retrieval of biological or chemical elements. The input sequence of bubbles/droplets encodes information, with the output being another sequence of bubbles/droplets or on-chip chemical synthesis. For performing a set of reactions/tasks or process control, the modulators can be used to program the device by producing a precisely timed sequence of bubbles/droplets, resulting in a cascade of logic operations within the micro- or nanofluidic channel sequence, utilizing the generated droplets/bubbles as a control. The devices are based on the principle of minimum energy interfaces formed between the two fluid phases enclosed inside precise channel geometries.

Abstract: A diagnostic device is provided that includes a plurality of retainment regions interconnected through at least one fluid processing passageway or separated by at least one barrier. A fluid flow modulator can be provided in the fluid processing passageway if a fluid processing passageway is provided. The barrier and/or fluid flow modulator can comprise a polysaccharide, a derivative of a polysaccharide, or a combination thereof. For example, the barrier can comprise a chitosan material.

Abstract: To provide a sensing device using a piezoelectric sensor having an oscillation area for detection and an oscillation area for reference and capable of achieving a high measurement sensitivity by improving shapes of excitation electrodes. On a quartz-crystal piece 20a, there are provided strip-shaped left side area and right side area which are formed symmetrically to be separated from each other into left and right with respect to a center of a circle 53 being a contour of a planar shape of a reaction channel 52 and extend in a longitudinal direction in a parallel manner.

Abstract: There is provided a microchip having an introduction portion introducing a liquid, a valve, and an ejection portion ejecting the liquid. The valve connects the introduction portion and the ejection portion, and retains the liquid such that surface tension of the liquid prevents the liquid from being ejected to the ejection portion. The liquid can be ejected from the introduction portion to the ejection portion by applying to the liquid centrifugal force larger than the surface tension of the liquid. Such a microchip according to the present invention has a simple configuration and allows easy control of retaining and flowing of a liquid.

Abstract: In accordance with the invention, there are surfaces exhibiting anisotropic wetting, microfluidic devices and microreactors including the surfaces and methods of controlling anisotropic wetting behavior of the surfaces. The exemplary surface can include a substrate and a plurality of rectangular shaped structures arranged to form a macroscopic pattern over the substrate, wherein the plurality of rectangular shaped structures delineate a top surface of the rectangular structures from a surface of the substrate, the rectangular shaped structures including substantially vertical walls having a height of about 100 nm to about 10 ?m and wherein the shape of the macroscopic pattern, the height of the substantially vertical walls, and a surface chemistry of the top surface controls anisotropic wetting at the top surface of the rectangular structures.

Abstract: A chip with tri-layer electrodes and micro-cavity arrays for control of bioparticles and a manufacturing method thereof are revealed. The chip captures and releases bioparticles into and from preset cavities by dielectrophoresis (DEP) force generated by electrodes. The chip includes an upper layer body, a middle layer body, a lower layer body, respectively disposed with an electrode, and micro flow chambers. The electrodes of the upper layer body and the middle layer body are common electrodes while the electrode of the lower layer body is a dispersive electrode array exposed on the bottom of lower-layer microcavity. The cell capture and release at the single-cell level and the cell population level are attained by application of an AC electric field.

Abstract: Provided is a biochemical analyzer including: a microfluidic device loading space including a microfluidic device supporting unit detachably supporting a microfluidic device including an electromagnetic radiation application region in which electromagnetic energy is applied; an energy source loading space including an energy source applying the electromagnetic energy to the electromagnetic radiation application region; and an isolation wall isolating the microfluidic device loading space and the energy source loading space to prevent heat transfer between the microfluidic device loading space and the energy source loading space and including a transparent window through which the electromagnetic energy can be transmitted. A method of controlling an internal temperature of the biochemical analyzer is also provided.

Abstract: An object of the invention is to provide a cassette and a measuring apparatus that can filter a sample for the optical measurement of an optically active substance and clean a sample flow channel by using a simple configuration. More specifically, the invention is directed to a cassette which includes a filter for filtering out a measurement interfering component from a sample, a container containing the filter, a cleaning liquid or cleaning agent for cleaning a sample flow channel, and a storage tank for storing the cleaning liquid or cleaning agent, and to a measuring apparatus having such a cassette.

Abstract: A method for producing an image of an object within a chamber of a microfluidic device includes providing the microfluidic device having x, y, and z dimensions and a chamber depth center point located along the z dimension. The chamber depth center point is located a known z dimension distance from a fiducial marking embedded within the microfluidic device. The method also includes placing the microfluidic device within an imaging system that includes an optical device capable of detecting the fiducial marking. The optical device defines an optical path axially aligned with the z dimension and has a focal plane perpendicular to the optical path. When the focal plane is moved along the optical path, the fiducial marking is maximally detected when the focal plane is at the z depth in comparison to when the focal plane is not substantially in-plane with the z depth.

Abstract: An inertial particle focusing system for use with a particle having diameter (a) includes a curved microchannel into a substrate, said microchannel having a radius of curvature (r), and a channel hydraulic diameter (Dh), wherein the ratio of r to Dh satisfies the following criterion: 2ra2/Dh3?0.037.

Abstract: The present invention provides modified droplet actuator systems, software, and software-executed methods for use in droplet actuator operation and droplet actuator systems that are configured and programmed to execute such software. An aspect of the software components of the invention is an interface description file for each hardware component of a microfluidics system that allows hardware components to be changed without modifying the program for performing droplet operations protocols. Another aspect of the software components of the invention is the establishment of electrode-to-electrode relationships and other aspects of droplet actuator configurations, which may be used when programming droplet operations protocols. Another aspect of the software components of the invention is a physical design library of predefined electrode elements that may be used by a droplet actuator designer when constructing a layout of electrodes.

Abstract: [PROBLEMS] To increase the rate of gas transfer in gas exchangers. [MEANS FOR SOLVING PROBLEMS] A gas exchange chip comprises substrates (1,2); two flow channels (3,4) formed in the substrates (1,2) and each having an inlet port and an outlet port; and multiple grooves (9) interlinking the flow channels (3,4). The grooves (9) have the size of their sectional area predetermined and have at least a part of the internal surface thereof rendered hydrophobic so as to permit the transfer of gas component while inhibiting any liquid passage. A sample water containing carbon dioxide is caused to flow through one of the flow channels (3) while pure water is caused to flow through the other flow channel (4) to thereby transfer the carbon dioxide contained in the sample water into the pure water.

Abstract: A sheath flow system having a channel with at least one fluid transporting structure located in the top and bottom surfaces situated so as to transport the sheath fluid laterally across the channel to provide sheath fluid fully surrounding the core solution. At the point of introduction into the channel, the sheath fluid and core solutions flow side by side within the channel or the core solution may be bounded on either side by the sheath fluid. The system is functional over a broad channel size range and with liquids of high or low viscosity. The design can be readily incorporated into microfluidic chips without the need for special manufacturing protocols.

Abstract: A device includes a reception chamber (5) for a cell suspension having an open bottom (6) extending opposite a cell deposition area (7) of the analysis plate (1), the bottom (6) of the chamber (5) being in fluid communication with an absorption material (14) for cell preservation liquid for absorbing the latter and enabling a homogeneous decantation deposition on the deposition area (7), the absorption material (14) being provided about the cell deposition area (7). The absorption material (14) includes a compressed area (16) extending between the bottom (6) of the reception chamber (5) and the analysis plate (1) about the cell deposition area (7), and a non-compressed area (17) extending about the compressed area (16).

Abstract: The present invention relates to a method for classifying a liquid (1) in a known pipetting system for this liquid (1), the method being characterized in that the changes of a selected, measurable, and physically founded virtual parameter are detected as a data set typical for this liquid (1); this typical data set of the selected virtual parameter is compared to corresponding data sets of known liquids, and the liquid (1) is classified on the basis of this comparison. An especially preferred method and a device for classifying a liquid (1) relate to a device which comprises a fluid chamber (2), to which a measuring chamber (3) is connected, whose internal pressure is monitored using a pressure transducer (4). At least a first part (5) of this fluid chamber (2) may be brought into fluid connection with a sample (6) of this liquid (1).

Abstract: A reaction vessel with a bottom drain opening supporting a selected unpressured head of fluid by the surface tension of the fluid. A device processing zone includes a support for spaced rows of reaction vessels, passages communicating with their drain openings of supported vessels, and a pressure source for selectively draining fluid through the drain openings. Generally horizontal bar magnets are supported for selected vertical movement between the vessel rows. A dispensing head has X discharge openings selectively positionable over X selected reaction vessels. A metering pump mechanism selectively meters X a selected quantity of fluid a bulk supply (where X is at least four), and selectively pumps the metered selected quantities through the drain openings to the selected reaction vessels. Methods of drawing fluid from the vessels using the pressure source, and moving the magnets to form a pellet of analyte are also included.

Abstract: The present invention provides a streamline-based device and a method for using the device for continuous separation of particles including cells in biological fluids. The device includes a main microchannel and an array of side microchannels disposed on a substrate. The main microchannel has a plurality of stagnation points with a predetermined geometric design, for example, each of the stagnation points has a predetermined distance from the upstream edge of each of the side microchannels. The particles are separated and collected in the side microchannels.

Abstract: Apparatuses and methods for manipulating droplets on a printed circuit board (PCB) are disclosed. Droplets are actuated upon a printed circuit board substrate surface by the application of electrical potentials to electrodes defined on the PCB. The use of soldermask as an electrode insulator for droplet manipulation as well techniques for adapting other traditional PCB layers and materials for droplet-based microfluidics are also disclosed.

Abstract: A test module for concentrating pathogens in a biological sample, the test module having an outer casing with a receptacle for receiving the sample, a dialysis device in fluid communication with the receptacle and configured to separate the pathogens from other constituents in the sample, and, a lab-on-a-chip (LOC) device being in fluid communication with the dialysis device and configured to analyze the pathogens.

Abstract: A microfluidic device includes chambers for performing chemical, biochemical, or physical processes and a flow path connecting the chambers. A magnetic particle is moved through the chambers which are separated by a valve-like structure that enables passing-through of the magnetic particle from one chamber to another. At least one delaying structure delays movement of the magnetic particle along the flow path.

Abstract: The invention encompasses microfluidic microarray assemblies (MMA) and subassemblies and methods for their manufacture and use. In one embodiment, first and second channel plates are provided and are sealingly connected to a test chip in consecutive steps. Each plate includes microfluidic channels configured in a predetermined reagent distribution pattern. The test chip comprises a plurality of discrete test positions, each test position being located at the intersection between a first predetermined reagent pattern and a second predetermined reagent pattern, wherein at least one of said patterns is non-linear. The first channel plate allows the distribution of a first reagent on said test chip, wherein said first reagent is immobilized at said test positions. The second channel plate allows the distribution of a second reagent on said test chip, wherein said second reagent comprises a plurality of different test samples.

Abstract: A microchip including a first substrate with a groove formed on a substrate surface or a pass-through hole passing in a thickness direction of the substrate, and one or more second substrates laminated on a surface of the first substrate; the microchip including an optical measurement cuvette consisting of a space configured by the groove or the pass-through hole, and a substrate surface of the second substrate; wherein a side wall surface of the second substrate is positioned on an inner side than a side wall surface of the first substrate in at least one part of a side wall surface of the microchip, and a method of using the same are provided.

Abstract: A device is provided for facilitating preparation of a sample for imaging. The device includes a cartridge having a generally flat, upper surface, a lower surface, an input port extending between the upper and lower surfaces thereof and an output port extending between the upper and lower surfaces thereof. The cartridge includes a first recess in the lower surface thereof having a first end communicating with the input port and a second end communicating with the output port. A cover slip has an upper surface engageable with the lower surface of the cartridge such that a portion of the upper surface of the cover slip communicates with the recess in the lower surface of the recess.

Abstract: A micro-fluidic device comprises a body. The body defines pneumatic ports, chambers for receiving liquids, and a connecting conduit. Each port is sealed with a seal and is shaped to couple to a pneumatic conduit through the seal. At least some of the chambers each have a top opening and a bottom opening. The top openings are in fluid communication with corresponding ports. The bottom openings are in fluid communication with one another through the connecting conduit, which is above the bottom openings. Selective application of pneumatic pressures to the chambers through the pneumatic conduits can transfer a liquid from one chamber to another through the connecting conduit, for example, for processing bio-samples within the device.

Abstract: A device and methods for sample distribution through a channel in which an expandable valve provides a mechanism to regulate flow through the channel. The valve may be configured to exert a force on a membrane layer so as to substantially block a portion of the channel to retain the sample in a desired location and prevent flow past the valve mechanism between the channel and a chamber.

Abstract: A microfluidic method and device for focusing and/or forming discontinuous sections of similar or dissimilar size in a fluid is provided. The device can be fabricated simply from readily-available, inexpensive material using simple techniques.

Abstract: Disclosed is a microfluidic device including a microfluidic structure formed in a platform in which various examinations, such as an immune serum examination, can be automatically performed using the biomolecule microarray chip. The biomolecule microarray chip-type microfluidic device using a biomolecule microarray chip comprises: a platform which is rotatable; a microfluidic structure disposed in the platform, comprising: a plurality of chambers; a plurality of channels connecting the chambers each other; and a plurality of valves controlling flow of fluids through the channels, wherein the microfluidic structure controls flow of a fluid sample using rotation of the platform and the valves; and a biomolecule microarray chip mounted in the platform such that biomolecule capture probes bound to the biomolecule microarray chip contact the fluid sample in the microfluidic structure.

Abstract: The present invention provides for a reagent splitting/dispensing device and method that can prevent contamination of an operation fluid when a reagent dispensing nozzle is in a waiting state and prevent falling of a droplet. The reagent splitting/dispensing method includes disposing and adjusting an air layer between an interface of an operation fluid and a reagent aspirated and subsequently dispensed from a nozzle tip end in an reagent dispensing nozzle.

Abstract: Methods for determining one or more operating parameters for a timing protocol of a microfluidic circuit are provided. In some embodiments, wet out times are measured for certain flow channels, and start times, flow rates and/or other parameters are calculated so that the various fluids in the microfluidic cartridge arrive at certain locations at a desired time and/or in a desired sequence. To help compensate for process variations, one or more fluidic process monitor components/structures may be fabricated along with the functional components/structures of a microfluidic cartridge. Test may be performed on the process monitor components/structures to help identify process variations in the particular microfluidic cartridge at hand. By using the process monitor data, the timing protocol for a particular microfluidic cartridge may be made more accurate.

Abstract: Devices, instruments, systems and methods are provided in which a primary line that receives a biological fluid is selectively sampled by a plurality of collection chambers. Selective sampling occurs by selectively accessing the primary line and selective engagement of a sampling pump under control of a microprocessor. Further, the instrument housing reversibly houses a drive assembly and sample collection housing to permit the interchangeability of drive assemblies and collection housings and thus enhance sterility or reduction of cost.

Abstract: A microfluidic device includes a sample chamber accommodating a sample, a first sample distribution unit connected to the sample chamber and receiving the sample, a sample transfer unit connected to the first sample distribution unit and forming a path for transferring the sample, and including a first connection unit connected to the first sample distribution unit and a second connection unit, wherein the distance from the center of rotation to the second connection unit is greater than the distance from the center of rotation to the first connection unit, a second sample distribution unit connected to the second connection unit and receiving the sample transferred via the sample transfer unit after filling the first sample distribution unit, and first and second analysis units respectively connected to the first and second sample distribution units and analyzing ingredients of the sample.

Abstract: The invention relates to a mixing method for mixing at least one small quantity of liquid, in which a quantity of liquid is applied in a reaction region and at least one surface sound wave is reacted with the quantity of liquid. The invention relates further to a mixing device for mixing at least one quantity of liquid for performing the method of the present invention, a use of the device, and a method of analysis for bond strengths on surfaces.

Abstract: A microfluidic cartridge with solution reservoir-pump chamber is disclosed. The microfluidic cartridge comprises a channel-chamber layer, a sealing layer, a printed circuit board bound with magnetoresistive biochip. The channel-chamber layer includes at least a waste reservoir, a reaction-detection chamber, a solution reservoir-pump chamber and a plurality of micro-channels. Said solution reservoir-pump chamber realizes both functions of solution reservoir and pump chamber in a single structure. Said sealing layer is sealed with said channel-chamber layer to form an integrated microfluidic system with at least a waste reservoir, a reaction-detection chamber, a solution inlet, a solution reservoir-pump chamber and a micro-channel. Said solution reservoir-pump chamber in the present invention consists of elastic objects inside for sealing and pumping. Under pressure, said elastic object propels solution in the reservoir into said reaction-detection chamber via channels of said plurality of micro-channels.

Abstract: A microchip device of the present invention includes: a microchip in which a liquid flow path is formed for liquid to flow; a gas flow path provided along the liquid flow path; and a plurality of gap sections formed between the liquid flow path and the gas flow path and having one opening thereof facing the liquid flow path and the other opening thereof facing the gas flow path, the gap of the gap section being made so as to be gap through which gas can pass but the liquid cannot pass, and a gas liquid interface being formed at the gap section.

Abstract: Fluid analyte sensors include a photoelectrocatalytic element that is configured to be exposed to the fluid, if present, and to respond to photoelectrocatalysis of at least one analyte in the fluid that occurs in response to impingement of optical radiation upon the photoelectrocatalytic element. A semiconductor light emitting source is also provided that is configured to impinge the optical radiation upon the photoelectrocatalytic element. Related solid state devices and sensing methods are also described.

Abstract: The present invention relates to the use of cyclometalated iridium complexes for detecting poly(amino acids) including peptides, polypeptides, and proteins. Poly(amino acids) are detected in solution, in electrophorectic gels, and on solid supports, including blots. The method of the present invention is rapid, highly sensitive, and extremely facile.

Abstract: The present invention relates to microfluidic devices and methods for manipulating and analyzing fluid samples. The disclosed microfluidic devices utilize a plurality of microfluidic channels, inlets, valves, filter, pumps, liquid barriers and other elements arranged in various configurations to manipulate the flow of a fluid sample in order to prepare such sample for analysis.

Abstract: Embodiments of the invention include a wireless sensor, such as an RFID tag, that includes a substrate, an antenna disposed on the substrate, and an environmentally sensitive sensor material disposed over at least a portion of said substrate. Other embodiments an RFID tag and at least one antibody coupled to the RFID tag. The RFID tag includes a substrate, circuitry disposed on the substrate, and an antenna coupled to the substrate. The at least one antibody is capable of affecting the signals emanating from the RFID tag. Further embodiments include a detection system that includes a reader. Yet other embodiments include a method for detecting specific analytes. The method includes providing an RFID tag which emanates a first signal having a first frequency, and enabling the REID tag to emanate a second signal having a second frequency upon attraction of a specific analyte to the RFID tag.

Abstract: The present invention relates to a droplet-based nucleic acid amplification apparatus and system. According to one embodiment, a droplet microactuator is provided made using a first substrate including a fluorescing material and including a detection region for detecting a fluorescence signal from a droplet, which detection region is coated with a light absorbing, low fluorescence or non-fluorescing material.

Abstract: A device adapted to determine an analyte concentration of a fluid sample using a test sensor. The device comprises a display adapted to display information to a user. The device further comprises at least one user-interface mechanism adapted to allow the user to interact with the device. The device further comprises a body portion including at least one opening formed therein, the at least one opening being of sufficient size to receive the test sensor. The device further comprises a memory adapted to store a plurality of stored analyte concentrations. The device further comprises a processing feature adapted to inhibit the stored analyte concentrations from being displayed on the display.

Abstract: Provided is a microfluidic control apparatus that includes at least one control means and a microfluidic control chip. When the microfluidic control chip is loaded to the control means, a needle provided to the control means is inserted into a reaction solution storage chamber of the microfluidic control chip, in which the reaction solution storage chamber is sealed with a sealing tape. Thus, fluid connection is easily formed between the microfluidic control chip and the control means without leakage.

Abstract: A refill droplet facilitates the extraction of a droplet laterally from a channel in a microfluidic apparatus. Such extraction allows a discrete band of separated particles or solute molecules to be excised from a fluid stream and processed and analyzed separately. An extraction point is located along the length of the channel and includes an EWOD surface or similar microfluidic technology to extract a droplet. An opening in the channel opposite the extraction means is equipped with microfluidic technology to transport a refill droplet to the opening. The refill droplet is moved into the channel or column to occupy the area previously occupied by the extracted droplet. This prevents distortion or mixing of the bands of particles or molecules within the channel and prevents the draining of any portion of the fluidic system.

Abstract: The present invention concerns sample pick-up and metering devices, analytical test systems for determining an analyte in a sample liquid and their use for this purpose and methods for determining an analyte in a sample liquid. They comprise or use a sample pick-up and metering device according to the invention which consists of a support and a metering element integrated into the support for taking up a defined volume of sample liquid and a closed liquid compartment located on the support which contains a defined volume of a liquid where the liquid compartment on the support can be opened.

Abstract: Provided is a biosensor with precision, high accuracy, and high sensitivity capable of increasing measurement accuracy while allowing measurements to be performed anywhere at any time by anyone, and allowing measurement with a small amount of specimen. In a biosensor including a specimen application portion (12) and a development flow channel (2), the specimen application portion (12) is configured such that an application space (9) is enclosed by a space-forming member (8) made of a liquid impermeable material, and a reaction reagent (14) that contains a labeling-reagent is retained in a position facing the application space (9) of the space-forming member (8) in the specimen application portion (12) so that the reaction reagent can be dissolved into a liquid specimen applied to the application space (9).

Abstract: A device for blood-plasma separation and plasma-based blood analysis is described. The device uses blood samples smaller than 5 ?L, (directly from the finger) and flow is achieved with a degassing-driven flow technique that causes blood to flow spontaneously into air-filled dead-end channels without external pumping mechanisms.

Abstract: A delivery apparatus for selectively delivering one or more liquid reagents into a reaction or test chamber (2), especially of an assay apparatus, the apparatus comprising: one or more respective storage chambers (5,6) for containing the one or more liquid reagents and arranged generally above the reaction or test chamber (2); and a plunger element (4) arranged and operable for insertion into the mouth of a selected storage chamber so as to displace a selected reagent from therewithin into the reaction or test chamber (2) generally therebelow by gravitational liquid overflow from the mouth of the chamber. The apparatus may conveniently be provided as a discrete delivery unit, with the storage chambers (5,6) prefilled with the selected reagents.